Valve Timing Control Spool Segmented Drain Flow Paths
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Solution Overview
Problem
Existing valve opening/closing timing control devices face challenges in accurately shifting to a locked state, particularly at intermediate lock phases, due to fluid pressure issues and viscosity problems when using engine oil at low temperatures, leading to obstructed fluid flow and complex configurations requiring multiple hydraulic valves.
Innovation Solution
A valve opening/closing timing control device with a spool movable along the rotation axis in a connecting bolt, featuring separate internal flow paths for fluid supply and discharge, including a lock drain flow path and phase control drain flow path, allows for independent fluid discharge and improved pressure management, enabling rapid and reliable locking without additional hydraulic valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drain flow path is used inside the spool, then the device structure is simplified, but fluid flow obstruction occurs and locking reliability deteriorates
Solution Approach 1:
The single drain flow path is segmented into two separate drain flow paths: a first drain flow path for discharging fluid from the advance chamber and a second drain flow path for discharging fluid from the retard chamber. This segmentation prevents fluid flow obstruction and ensures reliable locking by allowing independent drainage of each chamber.
Solution Approach 2:
The spool acts as an intermediary element that controls the separation of drain flow paths. By positioning the spool to cover or uncover specific ports, it mediates between the need for structural simplicity and the requirement for reliable fluid discharge, enabling the system to switch between different drainage configurations.
2Productivity
If the drain flow path has a large cross-sectional area, then drainage capacity is improved, but pressure in the drain flow path increases due to centrifugal force at high rotation speeds
Solution Approach 1:
The drainage function is segmented into two separate flow paths, each handling a portion of the total fluid discharge. This reduces the volume of fluid in each path, thereby reducing centrifugal pressure effects while maintaining adequate drainage capacity through the combined effect of both paths.
Solution Approach 2:
The drain flow paths are arranged in different spatial dimensions and orientations within the spool structure. This dimensional arrangement allows the fluid to discharge through multiple directions, reducing the impact of centrifugal force in any single direction and lowering overall fluid pressure.
3Device complexity
If a single hydraulic valve controls both phase control and lock control, then the device structure is simplified, but the shifting to locked state becomes difficult at intermediate lock phases
Solution Approach 1:
The control functions are segmented by separating the drain flow paths for phase control and lock control. This allows the single hydraulic valve to operate independently for each function through the spool's positioning, enabling reliable shifting to locked state at intermediate lock phases while maintaining structural simplicity.
Solution Approach 2:
The spool is designed to be dynamically positionable at multiple locations along its axis, allowing the single hydraulic valve to dynamically switch between controlling phase adjustment and lock engagement. This dynamic positioning enables the system to adapt to different operational requirements without adding multiple valves.
4Quantity of substance
If engine oil is used as fluid at low temperatures, then the system operates with standard lubrication, but fluid viscosity increases and obstructs flow
Solution Approach 1:
The fluid discharge is segmented into separate paths, reducing the volume and velocity requirements in each path. This allows engine oil to flow more easily even at low temperatures by reducing the demand for high-flow-rate through a single path, thereby maintaining operational reliability in cold conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration simplifies the device structure, reduces pressure loss, and ensures high responsiveness and reliable locking even at low temperatures, eliminating the need for multiple hydraulic valves and complex oil passages.
Implementation Method 1
a fluid pressure to control a relative rotation phase
Implementation Method 2
the fluid is pressed to an inner peripheral wall of the spool by a centrifugal force
Implementation Method 3
a lock mechanism which includes a lock member capable of engaging with a recessed portion
Data Source
AI summary
A valve opening/closing timing control device includes: a driving side rotator synchronously rotating with a crankshaft of an internal combustion engine; a driven side rotator coaxially disposed with a rotation axis of the driving side rotator and integrally rotating with a valve opening/closing camshaft; advance and retard chambers formed between the driving side and driven side rotators; a lock mechanism including a lock member capable of engaging with a recessed portion on one of the driving side and driven side rotators and provided in the other of the driving side and driven side rotators; and a connecting bolt coaxially disposed with the rotation axis and connecting the driven side rotator to the camshaft. The connecting bolt includes an internal space, and an advance port, a retard port and a lock port are formed as through-holes, a valve unit accommodates a spool, and the spool includes an internal flow path.